Fine Distribution of Nanoparticles in a Plastic Matrix

The higher the molecular weight of the polystyrene (left: 3300 g/mol, right: 7600 g/mol) used for the coating, the farther apart are the individual nanoparticles in the plastic.

Nanoparticles are extremely tiny particles with a diameter of less than 100 nanometers that are incorporated into plastics as a filler, among other things. Unfortunately, because of interface effects, they tend to collect at a few locations in the matrix, instead of being distributed as individual particles throughout the matrix.

For industrial applications, however, uniform mixing of matrix and filler is very important, since this allows the properties of the composite to be modified in a reliable manner. A research team at the University of Bayreuth has now developed a process that improves the mixing characteristics of nanocomposites.

The starting point for the process: polymer chains that attach themselves to the nanoparticles. The attached polymer is oriented almost vertically with respect to the surface of the particle. Projecting outward like bristles, the polymer chains prevent the nanoparticles from coming too close together when they are being incorporated into the plastic matrix. How far apart the individual nanoparticles in the plastic are depends on the length of the polymer chains used for the coating. Using this process, it is thus possible to control the spacing of the particles very exactly, according to the researchers.

A future area of application for the new process could be production of high-performance solar cells on the basis of semiconducting nanoparticles incorporated into a plastic matrix. Additional research is targeted at the development of data storage media made from plastic with iron-containing nanoparticles.